1. Field of the Invention
The present invention relates generally to telecommunication receivers and particularly to reducing the effect of noise in a multi-channel communication receiver.
2. Related Art
In telecommunication system channel in general refers to a band of frequencies used for transferring desired information in digital system. For the purposes of this disclosure data and information are used interchangeably. Often such channels are implemented on various communication medium, for example, copper wire, air, or optical cable. Information transfer capacity of each communication medium is measured in terms of bandwidth/data rate (frequency range).
In order to achieve an increased data rate, also called information transfer capacity, multiple channels are combined to form a single logical channel between a transmitter and a receiver. Accordingly transmitter is implemented to suitably encode the data for transmission on multiple channels. The encoded data is then transmitted on multiple channels, such that the signal/carrier on each channel carries a portion of information.
Similarly, the receiver is implemented to receive encoded data from multiple channels and decode collectively to extract the desired information. Multi-channel system is often referred to as multi-carrier system since multiple carriers are used for transmitting on corresponding multi-channels.
Multiple channels may be implemented using a single communication medium. For example, the total frequency range supported by a medium is divided into multiple sub bands. The information is then collectively transmitted on each sub band. Discrete multitone (DMT) orthogonal frequency-division multiplexing (OFDM) system represents an example of such a multi-channel communication system.
Alternatively, multiple communication medium, each having a fixed bandwidth, may be combined to form multiple channels between a transmitter and a receiver. The information is then transmitted collectively on each medium. For example, a number of individual copper wires, each having a fixed bandwidth, may be bundled to form a channel, collectively having larger bandwidth. A bonded DSL system represents an example of such communication system.
Signal on each channel is often affected from noise. One source of noise may be interference from the co-channels that are part of the multi-channel system, forming a single logical channel. Similarly, other channels that are not part of the logical channel but are in the vicinity may also cause interference as another source of noise.
Such noise often reduces the quality of the received signal thereby reducing the rate of data transfer (data rate) on a single channel and multiple channel system. Hence it is desirable to reduce the effect noise at the receiver.